Replacing the KDE Plasma widget ‘Thermal Monitor’ with ‘Kargos’ in Gentoo Linux

The KDE Plasma widget Thermal Monitor has not been working correctly in my Gentoo Linux installations for quite some time. I notice Thermal Monitor’s repository has not been updated for a couple of years, despite several new versions of KDE Plasma having been released. Perhaps that is the reason.

On my laptop running the Stable Branch of Gentoo Linux, Thermal Monitor displays the GPU and HDD temperatures automatically but CPU temperatures were only displayed if I right-clicked on the widget and selected ‘Reload Temperature Sources’. I managed to get the widget to display the CPU temperatures automatically by editing the file ~/.local/share/plasma/plasmoids/org.kde.thermalMonitor/contents/ui/main.qml and commenting out a line as shown in the file excerpt below:

[...]
        onSourceAdded: {

            if (source.indexOf(lmSensorsStart) === 0 || source.indexOf(acpiStart) === 0) {
/*
 *                systemmonitorAvailableSources.push(source)
 */
                var staIndex = systemmonitorSourcesToAdd.indexOf(source)
                if (staIndex > -1) {
                    addToSourcesOfDatasource(systemmonitorDS, source)
                    systemmonitorSourcesToAdd.splice(staIndex, 1)
                }

            }

        }
[...]

The above modification is suggested in a comment to Issue #53 in the widget’s repository.

However, the above-mentioned edit does not fix Thermal Monitor on my laptop running the Testing Branch of Gentoo Linux, and Thermal Monitor no longer displays the GPU temperature either. Actually, the CPU’s four core temperatures and the GPU temperature are no longer listed in the Thermal Monitor configuration window, only a single CPU temperature. Not surprisingly, none of the suggested changes to the file ~/.local/share/plasma/plasmoids/org.kde.thermalMonitor/contents/ui/main.qml that I found in Web searches made a difference. However, while researching the problem I came across a Manjaro Forums post by user bogdancovaciu about the Kargos Plasma widget, a KDE Plasma port of GNOME Argos and OSX BitBar. Kargos enables you to create a Plasma widget that runs your own script, which can be written in any language, providing its output adheres to a specified format. I also found a repository named k-argos-plugins containing further example scripts for Kargos. As none of the solutions suggested for Thermal Monitor in that Manjaro thread worked for me, I decided to try the Kargos widget instead. It works a treat.

kargos widget on KDE Plasma Panel of my Compal NBLB2 laptop

Below I explain what I did to install and configure the Kargos widget on my KDE Panel in Gentoo Linux (see screenshot). The packages lm-sensors and hddtemp were already installed in my case, but if they had not been, I would have needed to install and configure them, so I have included those steps below.

1. Install and configure lm-sensors

root # emerge lm-sensors
root # rc-update add lm_sensors default
root # sensors-detect

In my case sensors-detect created the file /etc/modules-load.d/lm_sensors.conf containing only the following:

# Generated by sensors-detect on Sun Oct 27 03:07:08 2019
coretemp

2. Start lm-sensors now, rather than rebooting

root # /etc/init.d/lm_sensors start

3. I wanted to use the nc command in my shell script for Kargos, so I installed its package

root # emerge netcat

4. Install and configure hddtemp

root # emerge hddtemp
root # rc-update add hddtemp default

Specify in the config file /etc/conf.d/hddtemp which drives to check:

# Copyright 1999-2012 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2

# the hddtemp executable
HDDTEMP_EXEC=/usr/sbin/hddtemp

# various options to pass to the daemon
HDDTEMP_OPTS="--listen=127.0.0.1"

# a list of drives to check
HDDTEMP_DRIVES="/dev/sda"

5. Start hddtemp now, rather than rebooting

root # /etc/init.d/hddtemp start

6. Install Kargos

On the KDE Plasma Desktop, click on the ‘Desktop’ menu icon (the three horizontal lines in the top right corner of the Desktop) and select: ‘Unlock Widgets’ > ‘Add Widgets…’ > ‘Get New Widgets…’ > ‘Download New Plasma Widgets’. Search for, and install, ‘kargos’ widget.

7. Create the Bash script ~/temperatures.3s.sh containing the following:

#!/bin/bash
temp=$(sensors | grep -oP 'Core.*?\+\K[0-9.]+')
temp0=$(sensors | grep 'Core 0' | cut -c '16-17')
temp1=$(sensors | grep 'Core 1' | cut -c '16-17')
temp2=$(sensors | grep 'Core 2' | cut -c '16-17')
temp3=$(sensors | grep 'Core 3' | cut -c '16-17')
hdd_temp=$(nc localhost 7634 | cut -c '33-34')
gpu_temp=$(sensors | grep -A 2 'radeon' | grep 'temp1' | cut -c '16-17')
echo "<br><font size='1'>CPU1&nbsp;&nbsp;CPU2&nbsp;&nbsp;CPU3&nbsp;&nbsp;CPU4&nbsp;&nbsp;GPU&nbsp;&nbsp;HDD</font><br>${temp0%%.*}°&nbsp;&nbsp;${temp1%%.*}°&nbsp;&nbsp;${temp2%%.*}°&nbsp;&nbsp;${temp3%%.*}°&nbsp;${gpu_temp}°&nbsp;${hdd_temp}°| font=Hack-Regular size=10"
# Uncomment the lines below if you want to be able to click on the kargos widget and display a pop-up TOP
#echo "---"
#TOP_OUTPUT=$(top -b -n 1 | head -n 20 | awk 1 ORS="\\\\n")
#echo "$TOP_OUTPUT | font=monospace iconName=htop"

The script above is specifically for the temperature sensors in my Clevo NBLB2 laptop. To find out which temperatures are available, and which characters to extract, use the following command:

root # sensors

Don’t forget to make the script executable:

user $ chmod +x ~/temperatures.3s.sh

Note that the ‘.3s‘ in the script name is optional but, if included, will override the kargos configuration (see further on) and run the script every 3 seconds. I could have specified another frequency, such as ‘.5s‘ or whatever.

8. Add the kargos widget to the KDE Panel.

9. Right-click on the kargos widget on the KDE Panel and select ‘Configure kargos…’.

10. Configure the kargos widget

In the first box in the configuration window, enter the full path of the script:

/home/fitzcarraldo/temperatures.3s.sh

In the second box leave ‘Interval in seconds’ as ‘1‘. This is overridden anyway if the script filename includes the interval.

In the third box leave ‘Rotation delay in seconds’ as ‘6‘.

On the KDE Plasma Desktop, click on the Desktop menu icon (three horizontal lines) and select: ‘Lock Widgets’.

11. Depending on the font configuration for the KDE Desktop, it may be necessary to edit the Bash script ~/temperatures.3s.sh to change the font name or size, the number of non-breaking spaces between the names displayed on the top line, and the number of non-breaking spaces between the temperature values displayed on the bottom line.

How to enable a Windows application in WINE to access a Samba share on a NAS (continued)

In a 2016 post ‘How to enable a Windows application in WINE to access a Samba share on a NAS‘ I explained how to mount in Linux a networked SMB shared folder so that a Windows application running via WINE could access the folder as Drive Y: in order to open and save files in it. In that blog post I also listed a couple of Bash scripts to facilitate the mounting and unmounting of the SMB share for the WINEPREFIX used for the Windows application (~/.wine-pdfxve6 in the example I gave for PDF-XChange Editor, Version 6). However, as I have several Windows applications running via WINE on my machines, and I have used a different WINEPREFIX for each of them, I wanted to be able to mount the SMB share for whichever of those applications I happen to be using at the time. Therefore I modified the original Bash scripts as shown below. The Desktop Configuration files (.desktop files) to launch the scripts are essentially the same as in my earlier blog post; I have just removed the references to the specific Windows application. The four modified files are listed below. Obviously change the username, SMB share name and SMB server name to suit your own situation.

1. Bash script ~/mount_bsfnas1_brianfolder_share.sh

#!/bin/bash
mount_share () {
    echo
    echo "Enter your Linux account password below..."
    echo
    sudo ln -s /media/bsfnas1/brianfolder ~/$PREFIX/dosdevices/y:
    sudo mount.cifs //bsfnas1/brianfolder/ -o user=brianfolder,pass=enricocaruso,uid=$(id -u),gid=$(id -g) ~/$PREFIX/dosdevices/y:
}
echo
echo "This will mount the Samba share folder brianfolder on the bsfnas1 machine."
echo
echo
echo "== Select which WINEPREFIX you wish to use =="
echo
ls ~/.wine-* | grep .wine | awk -F'/' '{print NR " " substr($4, 1, length($4)-1)}'
NUMPREFIXES=$(ls ~/.wine-* | grep .wine | wc -l)
echo
read -p "Enter number (q to abort) and press ENTER: " CHOICE
if [ "$CHOICE" != "q" ] && [ "$CHOICE" -gt 0 ] && [ "$CHOICE" -le $NUMPREFIXES ]; then
    PREFIX=$(ls ~/.wine-* | grep .wine | awk -F'/' '{print NR " " substr($4, 1, length($4)-1)}' | grep "$CHOICE " | awk -F' ' '{print $2}')
    echo
    if [ ! -e ~/$PREFIX/dosdevices/y: ]; then
        mount_share
    else
        echo -n "~/$PREFIX/dosdevices/y: already exists. Is it OK to proceed anyway (y/n)? "
        read ANSWER
        if [ $ANSWER = "y" ]; then
            rm ~/$PREFIX/dosdevices/y:
            mount_share
        fi
    fi
    echo
fi
if grep -q "/media/bsfnas1/brianfolder" /proc/mounts; then
    echo "Samba share //bsfnas1/brianfolder is mounted for WINEPREFIX ~/$PREFIX ."
else
    echo "Samba share //bsfnas1/brianfolder is not mounted."
fi
echo
echo "You may now close this window."
read ANSWER
exit

2. Bash script ~/umount_bsfnas1_brianfolder_share.sh

#!/bin/bash
echo
echo "This will unmount the Samba share folder brianfolder on the bsfnas1 machine."
echo
echo "Enter your Linux account password below..."
echo
sudo umount ~/.wine-*/dosdevices/y: 2>/dev/null
echo
if grep -q "/media/bsfnas1/brianfolder" /proc/mounts; then
  echo "Samba share //bsfnas1/brianfolder is mounted."
else
  echo "Samba share //bsfnas1/brianfolder is not mounted."
fi
echo
echo "You may now close this window."
exit

3. Desktop Configuration file ~/Desktop/mount_bsfnas1_brianfolder_share.desktop

[Desktop Entry]
Comment[en_GB]=Mount bsfnas1 brianfolder share for current WINEPREFIX
Comment=Mount bsfnas1 brianfolder share for current WINEPREFIX
Exec=sh /home/fitzcarraldo/mount_bsfnas1_brianfolder_share.sh
GenericName[en_GB]=Mount bsfnas1 brianfolder share for current WINEPREFIX
GenericName=Mount bsfnas1 brianfolder share for current WINEPREFIX
Icon=media-mount
MimeType=
Name[en_GB]=mount_bsfnas1_brianfolder_share
Name=mount_bsfnas1_brianfolder_share
Path=
StartupNotify=true
Terminal=true
TerminalOptions=\s--noclose
Type=Application
X-DBUS-ServiceName=
X-DBUS-StartupType=none
X-KDE-SubstituteUID=false
X-KDE-Username=fitzcarraldo

4. Desktop Configuration file ~/Desktop/umount_bsfnas1_brianfolder_share.desktop

[Desktop Entry]
Comment[en_GB]=Unmount bsfnas1 brianfolder share for current WINEPREFIX
Comment=Unmount bsfnas1 brianfolder share for current WINEPREFIX
Exec=sh /home/fitzcarraldo/umount_bsfnas1_brianfolder_share.sh
GenericName[en_GB]=Unmount bsfnas1 brianfolder share for current WINEPREFIX
GenericName=Unmount bsfnas1 brianfolder share for current WINEPREFIX
Icon=media-eject
MimeType=
Name[en_GB]=umount_bsfnas1_brianfolder_share
Name=umount_bsfnas1_brianfolder_share
Path=
StartupNotify=true
Terminal=true
TerminalOptions=\s--noclose
Type=Application
X-DBUS-ServiceName=
X-DBUS-StartupType=none
X-KDE-SubstituteUID=false
X-KDE-Username=fitzcarraldo

Now when I double-click on the icon to mount the SMB share for a Windows application running via WINE, a terminal window pops up displaying the WINEPREFIXs currently installed on my machine:

This will mount the Samba share folder brianfolder on the bsfnas1 machine.


== Select which WINEPREFIX you wish to use ==

1 .wine-3dimviewer
2 .wine-myphoneexplorer
3 .wine-nbtscan
4 .wine-pdfxve6
5 .wine-PortableApps
6 .wine-radiant
7 .wine-symmetry
8 .wine-visio
9 .wine-xnviewmp

Enter number (q to abort) and press ENTER: 

Let’s say I want to use the Windows application XnViewMP. I would enter ‘9’ and press ‘Enter’. The rest of the interaction should be obvious:

This will mount the Samba share folder brianfolder on the bsfnas1 machine.


== Select which WINEPREFIX you wish to use ==

1 .wine-3dimviewer
2 .wine-myphoneexplorer
3 .wine-nbtscan
4 .wine-pdfxve6
5 .wine-PortableApps
6 .wine-radiant
7 .wine-symmetry
8 .wine-visio
9 .wine-xnviewmp

Enter number (q to abort) and press ENTER: 9

~/.wine-xnviewmp/dosdevices/y: already exists. Is it OK to proceed anyway (y/n)? y

Enter your Linux account password below...

[sudo] password for fitzcarraldo: 

Samba share //bsfnas1/brianfolder is mounted for WINEPREFIX ~/.wine-xnviewmp .

You may now close this window.

Henceforth the Windows application XnViewMP will be able to access the Y: drive which is actually the SMB share //bsfnas1/brianfolder.

Once I have finished using the application, I just double-click on the the icon to unmount the SMB share, and a terminal window pops up displaying the following:

This will unmount the Samba share folder brianfolder on the bsfnas1 machine.

Enter your Linux account password below...

[sudo] password for fitzcarraldo: 

Samba share //bsfnas1/brianfolder is not mounted.

You may now close this window.

Once I have entered my Linux password for the local machine, the script will unmount the SMB share and the terminal window will close automatically if you have configured the Desktop Configuration file by right-clicking on the icon and unticking ‘Do not close when command exits’ in KDE, ‘Keep terminal window open after command execution’ in LXDE, or similar in other desktop environments.

Note: If you use Microsoft Office via WINE, you also might be interested in a comment on my earlier blog post about a Microsoft Office problem in saving files to a remote SMB share.

Creating a RAID of USB pendrives in Linux

USB hub and pendrives used as RAID10 with my laptop.

If you’re not familiar with the RAID (Redundant Array of Inexpensive Disks) concept and the different types of array, the article ‘RAID 0, RAID 1, RAID 5, RAID 10 Explained with Diagrams‘ gives a quick summary (and links to another article ‘RAID 2, RAID 3, RAID 4, RAID 6 Explained with Diagram‘). Another helpful article is ‘RAID Levels Explained‘.

A few years ago I came across a YouTube video by a Mac user, titled ‘Use a bunch of USB Flash drives in a RAID array‘. Purely out of interest he had experimented with creating RAIDs using USB pendrives (also known as ‘USB flash drives’ or ‘USB memory sticks’). The creation of a RAID using USB pendrives for his Apple Macs was very easy, and, since then, I had wanted to try this using one of my laptops running Linux, just to satisfy my curiosity. I have previously created software RAIDs in a Linux server using internal 3.5-inch HDDs, for the root, home and swap partitions, and for file storage partitions for a Cloud server and NAS. However, I had never created a RAID using external USB drives. This week I happened to have a spare four-port USB 3.0 hub and four old 4GB USB 2.0 pendrives, so I finally got the chance to create a RAID with USB pendrives (see photo). I decided to use my main laptop, which has Gentoo Linux with OpenRC, elogind, eudev and KDE installed. That installation does not have an initramfs so I did not need to rebuild an initramfs to assemble the RAID. Anyway, early assembly of a RAID by an initramfs would only be needed if the RAID were being used to hold the directories required by the OS (the root partition, for example). As my RAID would be pluggable external storage, I wanted to mount it manually rather than adding it to /etc/fstab to be mounted automatically at boot. As I had not used a RAID on this laptop before, I had not enabled the RAID drivers in the kernel configuration, so I needed to do that and rebuild the kernel. I opted to make the RAID drivers kernel modules rather than built into the kernel, so that I could load only the relevant module for whichever type of RAID I wished to create.

I had to decide which filesystem to use in the RAID. I have always used ext4 in my RAIDs using HDDs. However, F2FS is an interesting filesystem developed by Samsung for devices using flash memory, such as SD cards, USB pendrives and SSDs. So I decided to format the pendrives to use F2FS, and create an F2FS RAID. As I had not used F2FS previously on this laptop, I had not enabled the F2FS driver in the kernel configuration, so I enabled the F2FS driver in the kernel at the same time as I enabled the RAID drivers. As with the RAID drivers, I opted to make the F2FS driver a kernel module rather than built into the kernel, so that I could load it and unload it whenever I wanted.

Not only did it turn out to be easy to create a RAID using USB pendrives, I found that the Linux RAID module gets loaded automatically when I connect the USB hub. Furthermore the RAID is recognised by KDE and listed under ‘Places’ in the Dolphin file manager’s windows, which I can click on to mount and unmount the RAID. So I did not even need to configure the OS to load the RAID module at boot (the OS does not load the module automatically at boot if the hub is not connected).

DigitalOcean produced a good tutorial on creating RAIDs in Ubuntu: ‘How To Create RAID Arrays with mdadm on Ubuntu 16.04‘. The procedure is essentially the same in Gentoo Linux, the only differences being the path of the mdadm.conf file and the method of updating an initramfs (which I did not need to do anyway in this particular installation).

As I had four spare USB pendrives and a four-port hub, I decided to create a RAID10 array. Below is a summary of the steps I took.

1. I rebuilt the kernel in order to build the RAID and F2FS modules. The relevant kernel configuration parameters I set are shown below:

root # grep RAID /usr/src/linux/.config | grep -v "#"
CONFIG_MD_RAID0=m
CONFIG_MD_RAID1=m
CONFIG_MD_RAID10=m
CONFIG_MD_RAID456=m
CONFIG_ASYNC_RAID6_RECOV=m
CONFIG_RAID6_PQ=m
root # grep F2FS /usr/src/linux/.config | grep -v "#"
CONFIG_F2FS_FS=m
CONFIG_F2FS_STAT_FS=y
CONFIG_F2FS_FS_XATTR=y
CONFIG_F2FS_FS_POSIX_ACL=y

root # uname -a
Linux clevow230ss 4.19.72-gentoo #2 SMP Tue Oct 15 01:36:57 BST 2019 x86_64 Intel(R) Core(TM) i7-4810MQ CPU @ 2.80GHz GenuineIntel GNU/Linux

2. I installed the mdadm tool:

root # eix -I mdadm
[I] sys-fs/mdadm
     Available versions:  4.1^t {static}
     Installed versions:  4.1^t(01:52:17 15/10/19)(-static)
     Homepage:            https://git.kernel.org/pub/scm/utils/mdadm/mdadm.git/
     Description:         Tool for running RAID systems - replacement for the raidtools

3. I installed the F2FS tools:

root # eix -I f2fs
[I] sys-fs/f2fs-tools
     Available versions:  1.10.0(0/4) 1.11.0-r1(0/5) 1.12.0-r1(0/6) ~1.13.0(0/6) {selinux}
     Installed versions:  1.12.0-r1(0/6)(02:05:17 15/10/19)(-selinux)
     Homepage:            https://git.kernel.org/cgit/linux/kernel/git/jaegeuk/f2fs-tools.git/about/
     Description:         Tools for Flash-Friendly File System (F2FS)

4. I rebooted the laptop.

5. The f2fs module was not loaded automatically, therefore I loaded it manually and edited /etc/conf.d/modules to add the module name so that it would be loaded automatically in future:

root # modprobe f2fs
root # lsmod | grep f2fs
f2fs                  466944  0

root # nano /etc/conf.d/modules
root # grep ^modules /etc/conf.d/modules
modules="fuse bnep rfcomm hidp uvcvideo cifs mmc_block snd-seq-midi iptable_raw xt_CT uinput f2fs"

6. I plugged the four USB pendrives into the USB hub, and connected the hub to the laptop.

7. I launched GParted, deleted the existing partition on each pendrive (three had been formatted as FAT32, one as exFAT), reformatted them individually as F2FS and gave them each a label (USBPD01 to USBPD04). I could have done all that from the command line but it is easier using GParted, and I like an easy life.

Note that the mdadm USE flag in Gentoo Linux needed to be set when GParted was merged, so GParted would need to be re-merged with USE="mdadm" if that is not the case. Furthermore, GParted will only include F2FS in the list of available filesystems if either the F2FS module is loaded or the F2FS driver has been built into the kernel.

8. I ascertained the names of the USB pendrives:

root # lsblk -o NAME,SIZE,FSTYPE,TYPE,MOUNTPOINT
NAME     SIZE FSTYPE TYPE MOUNTPOINT
sda    698.7G        disk
├─sda1   128M ext2   part
├─sda2    16G swap   part [SWAP]
├─sda5   128G ext4   part /
├─sda6   256G ext4   part /home
└─sda7 298.5G ntfs   part /media/NTFS
sdb      3.8G        disk
└─sdb1   3.8G f2fs   part
sdc      3.8G        disk
└─sdc1   3.8G f2fs   part
sdd      3.8G        disk
└─sdd1   3.8G f2fs   part
sde      3.8G        disk
└─sde1   3.8G f2fs   part

As you can see above, the four USB pendrives are sdb to sde.

9. I loaded the raid10 module:

root # modprobe raid10
root # lsmod | grep raid
raid10                 57344  1

10. I created the RAID10 array:

root # mdadm --create --verbose /dev/md0 --level=10 --raid-devices=4 /dev/sdb /dev/sdc /dev/sdd /dev/sde
mdadm: layout defaults to n2
mdadm: layout defaults to n2
mdadm: chunk size defaults to 512K
mdadm: partition table exists on /dev/sdb
mdadm: partition table exists on /dev/sdb but will be lost or
       meaningless after creating array
mdadm: partition table exists on /dev/sdc
mdadm: partition table exists on /dev/sdc but will be lost or
       meaningless after creating array
mdadm: partition table exists on /dev/sdd
mdadm: partition table exists on /dev/sdd but will be lost or
       meaningless after creating array
mdadm: partition table exists on /dev/sde
mdadm: partition table exists on /dev/sde but will be lost or
       meaningless after creating array
mdadm: size set to 3913728K
Continue creating array? y
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.

It takes a while for the RAID to be created, so I checked progress periodically as follows:

root # cat /proc/mdstat
Personalities : [raid10]
md0 : active raid10 sde[3] sdd[2] sdc[1] sdb[0]
      7827456 blocks super 1.2 512K chunks 2 near-copies [4/4] [UUUU]
      [>....................]  resync =  2.8% (222272/7827456) finish=23.8min speed=5308K/sec
      
unused devices: <none>

root # cat /proc/mdstat
Personalities : [raid10]
md0 : active raid10 sde[3] sdd[2] sdc[1] sdb[0]
      7827456 blocks super 1.2 512K chunks 2 near-copies [4/4] [UUUU]
      [========>............]  resync = 44.0% (3449856/7827456) finish=12.9min speed=5637K/sec
      
unused devices: <none>

root # cat /proc/mdstat
Personalities : [raid10]
md0 : active raid10 sde[3] sdd[2] sdc[1] sdb[0]
      7827456 blocks super 1.2 512K chunks 2 near-copies [4/4] [UUUU]
      [==============>......]  resync = 74.0% (5797760/7827456) finish=5.9min speed=5698K/sec
      
unused devices: <none>

root # cat /proc/mdstat
Personalities : [raid10]
md0 : active raid10 sde[3] sdd[2] sdc[1] sdb[0]
      7827456 blocks super 1.2 512K chunks 2 near-copies [4/4] [UUUU]
      
unused devices: <none>

11. I formatted the RAID:

root # sudo mkfs.f2fs -f /dev/md0

        F2FS-tools: mkfs.f2fs Ver: 1.12.0 (2018-11-12)

Info: Disable heap-based policy
Info: Debug level = 0
Info: Trim is enabled
Info: Segments per section = 1
Info: Sections per zone = 1
Info: sector size = 512
Info: total sectors = 15654912 (7644 MB)
Info: zone aligned segment0 blkaddr: 512
Info: format version with
  "Linux version 4.19.72-gentoo (root@clevow230ss) (gcc version 8.3.0 (Gentoo 8.3.0-r1 p1.1)) #2 SMP Tue Oct 15 01:36:57 BST 2019"
Info: [/dev/md0] Discarding device
Info: This device doesn't support BLKSECDISCARD
Info: This device doesn't support BLKDISCARD
Info: Overprovision ratio = 2.300%
Info: Overprovision segments = 179 (GC reserved = 94)
Info: format successful

The option ‘-f‘ forces mkfs to overwrite any existing filesystem. (I believe the same option is ‘-F‘ in Ubuntu, rather than ‘-f‘.)

12. I created a mount point so I could mount the RAID from the command line if I wanted:

root # mkdir -p /mnt/md0

13. I mounted the RAID from the command line and checked its size. In the case of RAID10 I would expect the size to be double the size of one of the formatted USB pendrives, i.e. approximtely 2 x 3.8GB = 7.6GB):

root # mount /dev/md0 /mnt/md0
root # df -h -x devtmpfs -x tmpfs
Filesystem      Size  Used Avail Use% Mounted on
/dev/root       126G   36G   84G  31% /
/dev/sda6       252G  137G  103G  57% /home
/dev/sda7       299G  257G   43G  86% /media/NTFS
/dev/md0        7.5G  419M  7.1G   6% /mnt/md0

root # blkid | grep -v sda
/dev/md0: UUID="d565c117-37e0-48eb-b635-a2fe70b83272" TYPE="f2fs"
/dev/sdb: UUID="d1288120-a161-4809-3e89-bb5f967df69b" UUID_SUB="45a488a0-5126-0b95-0c28-eb1f743f77c7" LABEL="clevow230ss:0" TYPE="linux_raid_member"
/dev/sdc: UUID="d1288120-a161-4809-3e89-bb5f967df69b" UUID_SUB="ef7de228-cf4d-c6bf-c74a-462a0e27f8bd" LABEL="clevow230ss:0" TYPE="linux_raid_member"
/dev/sdd: UUID="d1288120-a161-4809-3e89-bb5f967df69b" UUID_SUB="b5dd5c41-3ab2-fa38-bd28-0b965883775c" LABEL="clevow230ss:0" TYPE="linux_raid_member"
/dev/sde: UUID="d1288120-a161-4809-3e89-bb5f967df69b" UUID_SUB="16149e7e-5a96-ece6-65ba-25721bcee49f" LABEL="clevow230ss:0" TYPE="linux_raid_member"

So /dev/md0 looked correct.

14. I checked that nothing was already configured in mdadm.conf and added the array’s details to it:

root # grep -v "#" /etc/mdadm.conf
root # mdadm --detail --scan | sudo tee -a /etc/mdadm.conf
ARRAY /dev/md0 metadata=1.2 name=clevow230ss:0 UUID=d1288120:a1614809:3e89bb5f:967df69b
root # grep -v "#" /etc/mdadm.conf
ARRAY /dev/md0 metadata=1.2 name=clevow230ss:0 UUID=d1288120:a1614809:3e89bb5f:967df69b

15. As the RAID will have only a partition for file storage, and as the RAID array will not always be connected to the laptop, it does not need to be assembled automatically early during boot, so there is no need to add mdadm.conf to an initramfs (which this laptop does not have anyway) and no need to specify /dev/md0 in /etc/fstab to be mounted at boot.

16. I left the USB hub connected to the laptop and rebooted.

17. I checked that the modules were loaded at boot:

root # lsmod | grep raid
raid10                 57344  1
root # lsmod | grep f2fs
f2fs                  466944  0

18. I checked that the RAID had been assembled correctly at boot:

root # blkid | grep -v sda
/dev/sdb: UUID="d1288120-a161-4809-3e89-bb5f967df69b" UUID_SUB="45a488a0-5126-0b95-0c28-eb1f743f77c7" LABEL="clevow230ss:0" TYPE="linux_raid_member"
/dev/sdc: UUID="d1288120-a161-4809-3e89-bb5f967df69b" UUID_SUB="ef7de228-cf4d-c6bf-c74a-462a0e27f8bd" LABEL="clevow230ss:0" TYPE="linux_raid_member"
/dev/sdd: UUID="d1288120-a161-4809-3e89-bb5f967df69b" UUID_SUB="b5dd5c41-3ab2-fa38-bd28-0b965883775c" LABEL="clevow230ss:0" TYPE="linux_raid_member"
/dev/md0: UUID="d565c117-37e0-48eb-b635-a2fe70b83272" TYPE="f2fs"
/dev/sde: UUID="d1288120-a161-4809-3e89-bb5f967df69b" UUID_SUB="16149e7e-5a96-ece6-65ba-25721bcee49f" LABEL="clevow230ss:0" TYPE="linux_raid_member"

19. I rebooted a few times with and without the USB hub connected. The module raid10 only gets loaded if the USB hub is connected. If I reboot without the hub connected, raid10 is no longer loaded automatically at boot. If I plug in the hub after the laptop has booted, raid10 gets loaded and the RAID array is recognised by the OS.

20. I mounted the RAID from the command line and copied a file to it as root user:

root # mount /dev/md0 /mnt/md0
root # ls -la /mnt/md0
total 8
drwxr-xr-x 2 root root 4096 Oct 15 07:40 .
drwxr-xr-x 7 root root 4096 Oct 15 07:42 ..
root # cp ./Paper_sheet_sizes.png /mnt/md0
root # ls -la /mnt/md0
total 268
drwxr-xr-x 2 root root   4096 Oct 15 08:07 .
drwxr-xr-x 7 root root   4096 Oct 15 07:42 ..
-rw-r--r-- 1 root root 265760 Oct 15 08:07 Paper_sheet_sizes.png
root # umount /dev/md0
root # ls -la /mnt/md0
total 8
drwxr-xr-x 2 root root 4096 Oct 15 07:42 .
drwxr-xr-x 7 root root 4096 Oct 15 07:42 ..

However, /mnt/md0/ is owned by the root user, so user fitzcarraldo cannot copy files into it. Therefore I changed the ownership:

root # mount /dev/md0 /mnt/md0
root # ls -la /mnt/
total 28
drwxr-xr-x  7 root root 4096 Oct 15 07:42 .
drwxr-xr-x 22 root root 4096 Oct  6 08:31 ..
-rw-r--r--  1 root root    0 Apr  9  2015 .keep
drwxr-xr-x  2 root root 4096 Apr 19  2015 cdrom
drwxr-xr-x  2 root root 4096 Jan 16  2017 floppy
drwxr-xr-x  2 root root 4096 Oct 15 08:07 md0
drwxr-xr-x  2 root root 4096 Apr 17  2015 pendrive
drwxr-xr-x  2 root root 4096 Mar 18  2016 usbstick
root # chown fitzcarraldo:fitzcarraldo /mnt/md0
root # ls -la /mnt/
total 28
drwxr-xr-x  7 root         root         4096 Oct 15 07:42 .
drwxr-xr-x 22 root         root         4096 Oct  6 08:31 ..
-rw-r--r--  1 root         root            0 Apr  9  2015 .keep
drwxr-xr-x  2 root         root         4096 Apr 19  2015 cdrom
drwxr-xr-x  2 root         root         4096 Jan 16  2017 floppy
drwxr-xr-x  2 fitzcarraldo fitzcarraldo 4096 Oct 15 08:07 md0
drwxr-xr-x  2 root         root         4096 Apr 17  2015 pendrive
drwxr-xr-x  2 root         root         4096 Mar 18  2016 usbstick
root # umount /dev/md0

21. ‘Places’ in Dolphin shows /mnt/md0 as ‘7.5 GiB Hard Drive’.

22. I can still mount the RAID from the command line:

root # mount /dev/md0 /mnt/md0
root # df -h /dev/md0
Filesystem      Size  Used Avail Use% Mounted on
/dev/md0        7.5G  420M  7.1G   6% /mnt/md0
root # umount /dev/md0

23. If I want to use the RAID in KDE I must use Dolphin to mount it, not mount it from the command line. To do this I click on the RAID ‘7.5 GiB Hard Drive’ listed under ‘Places’, and a window pop-ups prompting me to enter the root user’s password.

If I mount /dev/md0 via Dolphin instead of via the command line, KDE mounts it on a different directory:

root # df -h /run/media/fitzcarraldo/d565c117-37e0-48eb-b635-a2fe70b83272/
Filesystem      Size  Used Avail Use% Mounted on
/dev/md0        7.5G  420M  7.1G   6% /run/media/fitzcarraldo/d565c117-37e0-48eb-b635-a2fe70b83272

If I want to unmount it, I right-click on the RAID in ‘Places’ and select ‘Unmount’ in the right-click menu. Once it has been unmounted, I can unplug the hub from the laptop. If I plug the hub back into the laptop, the RAID is detected and can be mounted as usual.

So, it works! A USB hub and pendrives are a handy way to:

• experiment with creating the various types of RAID;
• compare the capacity of the RAID with the capacity of the USB pendrives used;
• measure the time to write and read a large file to/from the RAID and compare those times with the time to write and read the same file to/from a single USB pendrive of the same model.

Firewall zones (profiles) in Linux, and how to switch them automatically if you use UFW

Firstly, a note on terminology: UFW (Uncomplicated Firewall) and its two GUI front-ends Gufw and UFW Frontends use the term ‘application profile’ to refer to a pre-configured set of rules specified in a file. Files containing UFW application profiles are placed in the directory /etc/ufw/applications.d/. An application profile for SMB, for example, enables the root user to use the UFW command ‘ufw allow Samba‘ (‘ufw allow CIFS‘ in Gentoo Linux) rather than having to enter UFW commands specifying the precise ports and network protocols that SMB uses. However, this blog post is not about UFW’s application profiles; it is about what Gufw calls ‘profiles’ and firewalld calls ‘zones’.

In essence a profile/zone is a collection of firewall policies and rules. Both Gufw and firewalld include the concept of a ‘zone’, although Gufw uses the term ‘profile’ rather than ‘zone’. UFW Frontends does not have the concept of a ‘zone’; rules entered via UFW Frontends apply to any network to which you connect your laptop. The ability to define different zones for different networks is handy. For example, you can have certain policies and rules when your laptop is connected to your home network, and different policies and rules when your laptop is connected to the network in a café, hotel, airport or other public place.

An attractive feature of firewalld when used in conjunction with NetworkManager and KDE Plasma is that it is possible to use the desktop environment’s network management module (‘System Settings’ > ‘Connections’) to specify a particular firewalld zone for a particular network connection. For example, let’s say you used firewalld to specify certain policies and rules for a zone you named ‘office’, and you then specified in the System Settings – Connections GUI that a connection named ‘ACM’ should use the zone ‘office’. Thereafter, whenever you connect your laptop to the network named ‘ACM’, firewalld will use the policies and rules you previously configured for the zone ‘office’.

Unlike firewalld, Gufw does not have the ability to switch profiles automatically according to which network the laptop is connected. You have to select manually the profile you wish to use. You would launch Gufw prior to connecting to, for example, your office’s network, select the profile ‘Office’ (or whatever you have named it), then connect your laptop to that network.

I think many people would be satisfied with the functionality currently provided by Gufw. I could use the Gufw GUI to create Gufw profiles with names such as ‘Home’, ‘HomeDave’, ‘Public’, ‘HQoffice’, ‘USoffice’, ‘PestanaRio’ and so on, and specify the different policies and rules I want for each profile. At home I would launch Gufw on my laptop and select the Home profile then connect to my home network; in the office at work I would launch Gufw on my laptop and select the HQoffice profile then connect to the office network; at my friend Dave’s house I would launch Gufw on my laptop and select the HomeDave profile then connect to the house network; and so on. Nevertheless I do see the attraction of automated zone switching, as provided by firewalld in conjunction with NetworkManager and KDE. It would be handy if my laptop could switch automatically to the Home profile when my laptop connected to the network at my home with the name ‘BTHub5-8EUQ’, automatically switch to the HQoffice profile when my laptop connected to the network named ‘HQ-Office2’ in the office, and so on.

I use UFW on my two laptops running Gentoo Linux. The package ufw-frontends is also installed but normally I use UFW directly via the command line. However I wanted to learn about zones/profiles while using UFW, and I also wanted to see if I could automate the switching of zones without resorting to installing firewalld. NetworkManager has the ability to launch ‘hook’ scripts when certain things happen — when a network connection changes, for example — and this seemed to me to be a way of switching profiles automatically.

I had not used Gufw before, so I decided to install it. A package is available in many Linux distributions but there is no ebuild for Gufw in Gentoo’s main Portage tree and I could not find an up-to-date ebuild for it in any Portage overlays. Therefore I created the ebuild for net-firewall/gufw-19.10.0 shown below. It probably needs improving, but it does install a working Gufw in Gentoo Linux.

# Copyright 1999-2019 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Header: $

EAPI=7
PYTHON_COMPAT=( python3_{5,6,7} )
DISTUTILS_IN_SOURCE_BUILD=1

inherit distutils-r1

MY_PN="gui-ufw"
MY_PV="$(ver_cut 1-2)"

DESCRIPTION="GUI frontend for managing ufw."
HOMEPAGE="https://gufw.org/"
SRC_URI="https://launchpad.net/${MY_PN}/trunk/${MY_PV}/+download/${MY_PN}-${PV}.tar.gz"

LICENSE="GPL-3"
SLOT="0"
KEYWORDS="~amd64"
IUSE=""

DEPEND="dev-python/python-distutils-extra"
RDEPEND="net-firewall/ufw
	dev-python/netifaces
	dev-python/pygobject:3
	net-libs/webkit-gtk[introspection]
	sys-auth/elogind
	sys-auth/polkit
	x11-libs/gtk+:3[introspection]
	x11-themes/gnome-icon-theme-symbolic
"
S=${WORKDIR}/${MY_PN}-${PV}

pkg_postinst() {
	sed '/dist-packages/d' -i /usr/bin/gufw-pkexec
	sed -E '/\/share\//d' -i /usr/bin/gufw-pkexec
	local PYTHONVERSION="$(python -c 'import sys; print("{}.{}".format(sys.version_info.major, sys.version_info.minor))')"
	sed -E "s|python3\.[0-9]|python${PYTHONVERSION}|g" -i /usr/bin/gufw-pkexec
	sed -E 's|\/lib\/|\/lib64\/|g' -i /usr/bin/gufw-pkexec
}

‘How To Set Up a Firewall with GUFW on Linux‘ is a good tutorial on Gufw.

As I had not used Gufw previously, I had to play around with it to understand better its functional design. I found that if I configure rules directly via UFW on the command line without using Gufw, Gufw does not allow me to edit those rules (but does allow me to delete them) and those rules exist whichever Gufw profile is selected in the Gufw GUI. Gufw profiles are stored in files named ‘/etc/gufw/*.profile‘ (e.g. /etc/gufw/Home.profile) and these files will not include UFW rules entered via the command line. On the other hand, UFW rules created via the Gufw GUI apply solely to the currently-selected Gufw profile, which is what I would have expected. In other words, I can create a different set of policies and rules in each Gufw profile. Therefore I believe Gufw profiles (as distinct from UFW application profiles) are basically analogous to firewalld’s zones. It also appears to me that Gufw maintains configuration files specifying policies and rules independently of UFW, which Gufw then applies to UFW. In other words, if you are a Gufw user you should not use UFW directly to configure policies and rules, otherwise Gufw’s configuration files will not include what you did directly using UFW. To reiterate, use only Gufw or only UFW, not both.

The current Gufw profile’s name is listed in the file /etc/gufw/gufw.cfg. For example, I currently have the Home profile selected in the Gufw GUI, and the file gufw.cfg contains the following:

[GufwConfiguration]
profile = Home
windowwidth = 542
windowheight = 530
confirmdetelerule = yes

If I examine the contents of the file /etc/gufw/Home.profle I see that it contains the UFW policies and rules I specified for the Gufw Home profile:

[fwBasic]
status = enabled
incoming = deny
outgoing = allow
routed = disabled

[Rule0]
ufw_rule = 137,138/udp ALLOW IN 192.168.1.0/24
description = Samba
command = /usr/sbin/ufw allow in proto udp from 192.168.1.0/24 to any port 137,138
policy = allow
direction = in
protocol = 
from_ip = 192.168.1.0/24
from_port = 
to_ip = 
to_port = 137,138/udp
iface = 
routed = 
logging = 

[Rule1]
ufw_rule = 139,445/tcp ALLOW IN 192.168.1.0/24
description = Samba
command = /usr/sbin/ufw allow in proto tcp from 192.168.1.0/24 to any port 139,445
policy = allow
direction = in
protocol = 
from_ip = 192.168.1.0/24
from_port = 
to_ip = 
to_port = 139,445/tcp
iface = 
routed = 
logging =

I also notice that the other Gufw profiles can differ. For example, my Office.profile file contains the following:

[fwBasic]
status = enabled
incoming = deny
outgoing = allow
routed = allow

The profile name listed in gufw.cfg gets changed when the user changes the profile using the Gufw GUI. It appears to me that only at the point in time when the user selects a certain Gufw profile in the Gufw GUI does Gufw parse the applicable *.profile file and issue commands to UFW to implement the policies and rules specified in the *.profile file.

Initially I tried to automate the process of changing the Gufw profile by doing the following:

1. I created a NetworkManager Dispatcher hook script to:
   1. detect when the laptop connects to a network;

   2. determine whether the network is at my home, at my workplace or in a public place (café, airport or wherever) by looking at the connection name;

   3. edit gufw.cfg to change the name of the Gufw profile according to the network connected.
2. I configured KDE to launch Gufw automatically at login, hoping that would implement the Gufw profile specified in gufw.cfg.

When I connected the laptop to various networks, Gufw did indeed show the name of the profile selected by the NetworkManager Dispatcher hook script, but the associated Gufw profile’s rules had not been applied. They were only applied if I clicked on the ‘Profile’ pull-down menu in Gufw, selected a different Gufw profile, then re-selected the desired Gufw profile. Therefore driving Gufw from a NetworkManager Dispatcher hook script is not possible. This is a pity, as Gufw is an easy way to manage UFW from a GUI; it allows the user to create, delete and edit zones (Gufw profiles) and to select them manually. What Gufw doesn’t do is enable the user to associate those zones with connection names, nor trigger specific zone automatically based on the selected network connection. firewalld, on the other hand, does enable the user to do both those things.

As my attempt at automating the switching of zones in Gufw had failed, I decided to create a NetworkManager Dispatcher hook script to switch zones automatically by using UFW commands. Initially I though about creating a bespoke UFW application profile for each zone and allowing/denying those in the script, but it is actually easier to use the fundamental UFW commands in the script, especially as UFW commands are relatively easy to understand. Also, this approach means everything is in a single file, which facilitates configuration. I can simply edit the script in order to: a) add or delete a zone; b) change a zone’s name; c) change policies and rules for a zone; d) add or delete a connection; e) change the name of a connection; f) change the zone a connection uses. Granted, editing a script is not as user-friendly as using the firewalld GUI to configure a zone and then using KDE Plasma’s system settings module Connections to specify that zone for a specific connection, but my script is not particularly difficult to understand and edit. And by using such a script I can continue to use UFW rather than installing firewalld and having to learn how to use it.

My NetworkManager Dispatcher hook script /etc/NetworkManager/dispatcher.d/20_ufw-zones is listed below. In the main body of the script I define the zone I wish to use for each connection, and in the function select_zone I define the policies and rules I want each zone to use.

#!/bin/bash
INTERFACE=$1
STATUS=$2
WIRED=enp4s0f1
WIFI=wlp3s0

CT_helper_rule() {
    echo "# The following is needed to enable Samba commands to" >> /etc/ufw/before.rules
    echo "# work properly for broadcast NetBIOS name resolution" >> /etc/ufw/before.rules
    echo "#"  >> /etc/ufw/before.rules
    echo "# raw table rules" >> /etc/ufw/before.rules
    echo "*raw" >> /etc/ufw/before.rules
    echo ":OUTPUT ACCEPT [0:0]" >> /etc/ufw/before.rules
    echo "-F OUTPUT" >> /etc/ufw/before.rules
    echo "-A OUTPUT -p udp -m udp --dport 137 -j CT --helper netbios-ns" >> /etc/ufw/before.rules
    echo "COMMIT" >> /etc/ufw/before.rules
}
 
select_zone() {
    ufw --force reset
    ufw --force enable
    ZONE=$1
    case "$ZONE" in
    'Home')
        ufw default deny incoming
        ufw default allow outgoing
        #
        # Rules for SMB
        ufw allow from 192.168.1.0/24 to any port 137,138 proto udp
        ufw allow from 192.168.1.0/24 to any port 139,445 proto tcp
        CT_helper_rule
        #
        # Rules for KDEConnect
        ufw allow from 192.168.1.0/24 to any port 1714:1764 proto udp
        ufw allow from 192.168.1.0/24 to any port 1714:1764 proto tcp
    ;;
    'Office')
        ufw default deny incoming
        ufw default allow outgoing
    ;;
    'Public')
        ufw default reject incoming
        ufw default allow outgoing
    ;;
    'JohnsHouse')
        ufw default deny incoming
        ufw default allow outgoing
        #
        # Rules for SMB
        ufw allow from 192.168.42.0/24 to any port 137,138 proto udp
        ufw allow from 192.168.42.0/24 to any port 139,445 proto tcp
        CT_helper_rule
        #
        # Rules for KDEConnect
        ufw allow from 192.168.42.0/24 to any port 1714:1764 proto udp
        ufw allow from 192.168.42.0/24 to any port 1714:1764 proto tcp
    ;;
    esac
    ufw --force reload
    rm /etc/ufw/*.rules.20* # Delete backups of *.rules files ufw makes every time it is reset
    echo -n `date +"[%F %T %Z]"` >> /var/log/ufw-zones.log
    echo " Zone $ZONE selected for connection $ACTIVE on interface $INTERFACE." >> /var/log/ufw-zones.log
}
 
# Check if either the wired or wireless interface is up
if [ "$INTERFACE" = "$WIRED" -o "$INTERFACE" = "$WIFI" ] && [ "$STATUS" = "up" ]; then
 
    # Check if a single connection is active
    if [ `nmcli c | grep -v "\-\-" | grep -v "NAME.*UUID.*TYPE.*DEVICE" | wc -l` -eq 1 ]; then
 
        # Ascertain the name of the active connection
        ACTIVE=`nmcli c | grep -v "\-\-" | grep -v "NAME.*UUID.*TYPE.*DEVICE" | awk -F' ' '{print $1}'`
 
        case "$ACTIVE" in
 
        'eth0')
            ZONE="Home"
        ;;
        'POR1-wired')
            ZONE="Office"
        ;;
        'BTHub5-8EUQ')
            ZONE="Home"
        ;;
        'BTHub5-8EUQ-5GHz')
            ZONE="Home"
        ;;
        'John1')
            ZONE="JohnsHouse"
        ;;
        'GRAND MERCURE')
            ZONE="Public"
        ;;
        *)
            # If connection name is not in above list
            ZONE="Public"
        ;;

        esac

        select_zone $ZONE
        exit $?

    fi
fi

The log file that the script uses contains a chronological record of the connections made and the zones selected:

$ cat /var/log/ufw-zones.log 
[2019-09-30 20:13:52 BST] Zone Home selected for connection eth0 on interface enp4s0f1.
[2019-10-01 22:59:18 BST] Zone Home selected for connection BTHub5-8EUQ-5GHz on interface wlp3s0.
[2019-10-02 17:59:23 EDT] Zone Public selected for connection loganwifi on interface wlp3s0.
[2019-10-03 10:12:46 EDT] Zone Office selected for connection POR1-wired on interface enp4s0f1.

Paul Gideon Dann’s patchset for Poppler to enable Okular (Qt5) to use Cairo rather than Splash to render PDF files

If you view the same PDF file in Okular (KDE) and Evince (GNOME), you may notice that fonts and lines are rendered better in Evince. Both applications use Poppler to render text and graphics in PDF files, but Poppler uses a different rendering backend in the two applications. For Evince Poppler uses the Cairo library, whereas for Okular Poppler uses Splash, a backend inherited from Poppler’s predecessor Xpdf (still in development). Unfortunately for KDE users, Cairo often does a better job than Splash. However, independent software engineer Paul Gideon Dann came to the rescue by producing the patchset poppler-cairo-backend to modify Poppler in order to make it use the Cairo library instead of Splash when Poppler is used by Okular. To quote the README file for Paul’s patchset:

Purpose of this Patchset

Currently, the default backend for the Qt5 wrapper (used by Okular) is Splash. Unfortunately, Splash does not support subpixel rendering of fonts, so those of us using KDE are stuck with somewhat ugly-looking fonts. This patchset adds support for the Cairo backend to the Qt5 wrapper. It also forces subpixel rendering in the Cairo backend. The upshot of this is that we get beautiful fonts in Okular.

The README focuses on fonts, but in fact the rendering of lines in graphics in PDF files can also be improved by the application of the patchset.

Apparently the Poppler maintainer feels that the introduction of a dependency on Cairo to the Qt5 wrapper (even an optional dependency) in Poppler would be controversial, and he is not willing to merge the patchset. For Okular users who already have Cairo installed (e.g. for Firefox, Inkscape, Scribus and so on), and who are noticing inadequate rendering of some PDF files, Paul’s patchset is worth trying.

In Gentoo Linux, which is a source code-based distribution, it is very easy to apply the patchset. For example, I did the following to apply the patchset for Poppler 0.80.0 in a ~amd64 (Testing Branch) installation:

1. Created a package-specific and version-specific directory to hold the patchset:

root # mkdir -p /etc/portage/patches/app-text/poppler-0.80.0

2. Downloaded the patchset for Poppler 0.80.0 from the following Web page:

https://github.com/giddie/poppler-cairo-backend/tree/76e607bcf010d6d9b8df5cb0f851ef9c91d4caf2

3. Copied the patchset to the directory created in Step 1:

root # cp /home/fitzcarraldo/Downloads/*.patch /etc/portage/patches/app-text/poppler-0.80.0/
root # ls -1 /etc/portage/patches/app-text/poppler-0.80.0
0001-Cairo-backend-added-to-Qt5-wrapper.patch
0002-Setting-default-Qt5-backend-to-Cairo.patch
0003-Apply-subpixel-rendering-in-Cairo-Backend.patch

4. Checked first that the patchset could be applied successfully before actually using it:

root # cd /usr/portage/app-text/poppler
root # ebuild poppler-0.80.0.ebuild clean prepare
 * poppler-0.80.0.tar.xz BLAKE2B SHA512 size ;-) ...                                     [ ok ]
 * checking ebuild checksums ;-) ...                                                     [ ok ]
 * checking auxfile checksums ;-) ...                                                    [ ok ]
 * checking miscfile checksums ;-) ...                                                   [ ok ]
>>> Unpacking source...
>>> Unpacking poppler-0.80.0.tar.xz to /var/tmp/portage/app-text/poppler-0.80.0/work
>>> Source unpacked in /var/tmp/portage/app-text/poppler-0.80.0/work
>>> Preparing source in /var/tmp/portage/app-text/poppler-0.80.0/work/poppler-0.80.0 ...
 * Applying poppler-0.60.1-qt5-dependencies.patch ...                                    [ ok ]
 * Applying poppler-0.28.1-fix-multilib-configuration.patch ...                          [ ok ]
 * Applying poppler-0.78.0-respect-cflags.patch ...                                      [ ok ]
 * Applying poppler-0.61.0-respect-cflags.patch ...                                      [ ok ]
 * Applying poppler-0.57.0-disable-internal-jpx.patch ...                                [ ok ]
 * Applying 0001-Cairo-backend-added-to-Qt5-wrapper.patch ...                            [ ok ]
 * Applying 0002-Setting-default-Qt5-backend-to-Cairo.patch ...                          [ ok ]
 * Applying 0003-Apply-subpixel-rendering-in-Cairo-Backend.patch ...                     [ ok ]
 * User patches applied.
>>> Source prepared.

5. Re-merged Poppler to apply the patchset to the Poppler source code and rebuild the patched package:

root # emerge -1v poppler

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild   R    ] app-text/poppler-0.80.0:0/90::gentoo  USE="cairo cjk cxx introspection jpeg jpeg2k lcms png qt5 tiff utils -curl -debug -doc -nss" 0 KiB

Total: 1 package (1 reinstall), Size of downloads: 0 KiB

>>> Verifying ebuild manifests
>>> Emerging (1 of 1) app-text/poppler-0.80.0::gentoo
>>> Installing (1 of 1) app-text/poppler-0.80.0::gentoo
>>> Jobs: 1 of 1 complete                           Load avg: 1.06, 1.11, 0.95
>>> Auto-cleaning packages...

>>> No outdated packages were found on your system.

 * GNU info directory index is up-to-date.

6. Re-merged Okular so that it uses the patched Poppler dependency:

root # emerge -1v okular

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild   R    ] kde-apps/okular-19.08.1:5::gentoo  USE="chm crypt djvu image-backend pdf postscript tiff -debug -epub -handbook -markdown -mobi -mobile -plucker -share -speech -test" 0 KiB

Total: 1 package (1 reinstall), Size of downloads: 0 KiB

>>> Verifying ebuild manifests
>>> Emerging (1 of 1) kde-apps/okular-19.08.1::gentoo
>>> Installing (1 of 1) kde-apps/okular-19.08.1::gentoo
>>> Jobs: 1 of 1 complete                           Load avg: 1.17, 1.13, 1.04
>>> Auto-cleaning packages...

>>> No outdated packages were found on your system.

 * GNU info directory index is up-to-date.

My thanks go to Paul for taking the time to produce the patchset.

How to change the height of the Kickoff Application Launcher menu in KDE Plasma

The height of the KDE Plasma Kickoff Application Launcher menu is not user-configurable, which is odd in a Desktop Environment with a reputation for being highly user-configurable.

It turns out that the height and width of the pop-up menu are hard-coded in the ASCII file /usr/share/plasma/plasmoids/org.kde.plasma.kickoff/contents/ui/FullRepresentation.qml:

root # grep -E "Layout.minimumHeight.*units.gridUnit" /usr/share/plasma/plasmoids/org.kde.plasma.kickoff/contents/ui/FullRepresentation.qml
    Layout.minimumHeight: units.gridUnit * 34

root # grep -E "Layout.minimumWidth.*units.gridUnit" /usr/share/plasma/plasmoids/org.kde.plasma.kickoff/contents/ui/FullRepresentation.qml
    Layout.minimumWidth: units.gridUnit * 26

Now, I was a bit fed up having to scroll up and down the launcher menu to see all fourteen entries in my Favourites list, so I decided to increase the height of the menu, which I did by editing /usr/share/plasma/plasmoids/org.kde.plasma.kickoff/contents/ui/FullRepresentation.qml as root user:

root # nano /usr/share/plasma/plasmoids/org.kde.plasma.kickoff/contents/ui/FullRepresentation.qml
root # grep -E "Layout.minimumHeight.*units.gridUnit" /usr/share/plasma/plasmoids/org.kde.plasma.kickoff/contents/ui/FullRepresentation.qml
    Layout.minimumHeight: units.gridUnit * 44

The only downside to this is that the file will be overwritten when the package kde-plasma/plasma-desktop is upgraded.

The following command would allow me to make sure the file contains the height value of ’44’ that I want:

root # sed -i '/Layout.minimumHeight: units.gridUnit/ c\    Layout.minimumHeight: units.gridUnit * 44' /usr/share/plasma/plasmoids/org.kde.plasma.kickoff/contents/ui/FullRepresentation.qml

Therefore, to automate the editing of the file in my Gentoo installations that use OpenRC I created a shell script /etc/local.d/50-set_Kickoff_height.start with the following contents:

#!/bin/bash
if [ -e /usr/share/plasma/plasmoids/org.kde.plasma.kickoff/contents/ui/FullRepresentation.qml ]; then
    sed -i '/Layout.minimumHeight: units.gridUnit/ c\    Layout.minimumHeight: units.gridUnit * 44' /usr/share/plasma/plasmoids/org.kde.plasma.kickoff/contents/ui/FullRepresentation.qml
fi

The FullRepresentation.qml file will then be edited every time the machine boots, which is a tad inefficient but not a big overhead.

This is not a perfect solution because the menu will revert to its default height following an upgrade to the package kde-plasma/plasma-desktop until I reboot the machine, but it is good enough for me.

How to change the keymap (keyboard layout) used by the GRUB shell in Gentoo Linux

The default keymap in the GRUB shell is US English. Because Linux has not yet been booted, the GRUB keymap is not governed by the keymap for the Linux console specified in /etc/conf.d/keymaps in the case of OpenRC, or in /etc/vconsole.conf in the case of systemd. This can be inconvenient if your keyboard has a different layout and you need to use the GRUB Rescue Shell. Below I explain how I configured my Gentoo Linux installation to be able to use a different keyboard layout in the GRUB shell.

There are, however, certain limitations to the keymap in the GRUB shell. The official GRUB documentation states the following:

17.4 Input terminal

Firmware console on BIOS, IEEE1275 and ARC doesn’t allow you to enter non-ASCII characters. EFI specification allows for such but author is unaware of any actual implementations. Serial input is currently limited for latin1 (unlikely to change). Own keyboard implementations (at_keyboard and usb_keyboard) supports any key but work on one-char-per-keystroke. So no dead keys or advanced input method. Also there is no keymap change hotkey. In practice it makes difficult to enter any text using non-Latin alphabet. Moreover all current input consumers are limited to ASCII.

Note that the GRUB documentation states ‘ASCII’, not ‘Extended ASCII’. ASCII is limited to codes 000 to 127 (see the character table in e.g. http://www.asciitable.com/).

Some Linux distributions have the utility grub-kbdcomp to generate a GRUB keyboard layout file. grub-kbdcomp is simply a shell script that is a wrapper for the Debian ckbcomp utility and grub-mklayout. There is a Gentoo Portage ebuild for ckbcomp:

root # eix ckbcomp
[I] sys-apps/ckbcomp
     Available versions:  (~)1.164
     Homepage:            https://anonscm.debian.org/cgit/d-i/console-setup.git
     Description:         Compile an XKB keymap for loadkeys

However, I noticed that the latest version currently available in Debian is 1.191 (https://salsa.debian.org/installer-team/console-setup.git), so I created an ebuild ckbcomp-1.191.ebuild in a local overlay on one of my laptops running Gentoo Linux Stable Branch, and I installed ckbcomp-1.191.

# Copyright 1999-2019 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2

EAPI=6

DESCRIPTION="Compile an XKB keymap for loadkeys"
HOMEPAGE="https://salsa.debian.org/installer-team/console-setup.git"

if [[ ${PV} == 9999 ]]; then
        inherit git-r3
        EGIT_REPO_URI="https://salsa.debian.org/installer-team/console-setup.git"
else
        SRC_URI="https://salsa.debian.org/installer-team/console-setup/-/archive/${PV}/${P}.tar.gz -> ${P}.tar.gz"
        KEYWORDS="~amd64"
        S="${WORKDIR}"
fi

LICENSE="GPL-2"
SLOT="0"

DEPEND=""
RDEPEND="
        dev-lang/perl:*
        sys-apps/kbd
        x11-misc/xkeyboard-config"

src_compile() {
        :
}

src_install() {
        dobin console-setup-${PV}-*/Keyboard/ckbcomp
}

I have tried the above-mentioned ckbcomp command on my PC BIOS Core i7 laptop running Gentoo Stable with OpenRC and GRUB Version 2.02-r3:

root # eix -I grub
[I] sys-boot/grub
     Available versions:  (2) 2.02-r3(2/2.02-r3)^st **9999(2/9999)^st
       {debug device-mapper doc efiemu +fonts libzfs mount multislot nls sdl static test +themes truetype GRUB_PLATFORMS="coreboot efi-32 efi-64 emu ieee1275 loongson multiboot pc qemu qemu-mips uboot xen xen-32"}
     Installed versions:  2.02-r3(2/2.02-r3)^st(02:33:36 23/03/19)(fonts nls sdl themes truetype -debug -device-mapper -doc -efiemu -libzfs -mount -multislot -static -test GRUB_PLATFORMS="pc -coreboot -efi-32 -efi-64 -emu -ieee1275 -loongson -multiboot -qemu -qemu-mips -uboot -xen -xen-32")
     Homepage:            https://www.gnu.org/software/grub/
     Description:         GNU GRUB boot loader

I used the following steps:

1. Installed sys-apps/ckbcomp.

root # emerge ckbcomp
root # eix ckbcomp
[I] sys-apps/ckbcomp
     Available versions:  (~)1.164 (~)1.191[1]
     Installed versions:  1.191[1](22:09:15 20/04/19)
     Homepage:            https://salsa.debian.org/installer-team/console-setup.git
     Description:         Compile an XKB keymap for loadkeys

[1] "local_overlay" /usr/local/portage

2. Created a new sub-directory to store the GRUB keyboard layout files.

root # mkdir /boot/grub/layouts

3. Converted the X11 keymap to the GRUB keymap. The option for ckbcomp must exist in the directory /usr/share/X11/xkb/symbols/ for this to work.

root # ckbcomp gb extd | grub-mklayout -o /boot/grub/layouts/gb.gkb
Unknown keyboard scan identifier Meta_Tab
Unknown keyboard scan identifier Meta_Tab
Unknown keyboard scan code 0x54
Unknown keyboard scan code 0x65
Unknown keyboard scan code 0x7f

I used the following commands to generate a br.gkb (Brazilian Portuguese keymap) file and a us.gkb (US English keymap) as well, as it is possible to switch keyboard layouts from the GRUB command line using the keymap command, as I show further on:

root # ckbcomp br nodeadkeys | grub-mklayout -o /boot/grub/layouts/br.gkb
Unknown keyboard scan identifier Meta_Tab
Unknown keyboard scan identifier Meta_Tab
Unknown keyboard scan identifier KP_Comma
Unknown keyboard scan identifier KP_Comma
Unknown keyboard scan identifier KP_Comma
Unknown keyboard scan identifier KP_Comma
Unknown keyboard scan code 0x54
Unknown keyboard scan code 0x65
Unknown keyboard scan code 0x7f
root # ckbcomp us | grub-mklayout -o /boot/grub/layouts/us.gkb
Unknown keyboard scan identifier Meta_Tab
Unknown keyboard scan identifier Meta_Tab
Unknown keyboard scan code 0x54
Unknown keyboard scan code 0x65
Unknown keyboard scan code 0x7f

The resulting files can be seen in the directory /boot/grub/layouts/:

root # ls -la /boot/grub/layouts
total 11
drwxr-xr-x 2 root root 1024 Apr 21 21:20 .
drwxr-xr-x 7 root root 1024 Nov 26 00:01 ..
-rw-r--r-- 1 root root 2572 Apr 21 21:29 br.gkb
-rw-r--r-- 1 root root 2572 Apr 21 21:29 gb.gkb
-rw-r--r-- 1 root root 2572 Apr 21 21:30 us.gkb

4. Append ‘GRUB_TERMINAL_INPUT=at_keyboard‘ to /etc/default/grub.

root # grep GRUB_TERMINAL_INPUT /etc/default/grub
GRUB_TERMINAL_INPUT="at_keyboard"

5. Add ‘insmod‘ and ‘keymap‘ lines to /etc/grub.d/40_custom as shown below.

root # tail -n 2 /etc/grub.d/40_custom
insmod keylayouts
keymap $prefix/layouts/gb.gkb

6. Check what locales are available for the keymap.

root # locale --all-locales | grep -i gb
en_GB
en_GB.iso88591
en_GB.utf8

7. Add ‘locale=en_GB‘ to GRUB_CMDLINE_LINUX.

root # grep locale /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="locale=en_GB i915.modeset=1 rcutree.rcu_idle_gp_delay=1 acpi_enforce_resources=lax reboot=force raid=noautodetect resume=/dev/sda2"

8. Regenerate the grub.cfg file.

root # grub-mkconfig -o /boot/grub/grub.cfg
root # grep terminal_input /boot/grub/grub.cfg
terminal_input at_keyboard
root # grep gkb /boot/grub/grub.cfg
keymap $prefix/layouts/gb.gkb
root # grep layouts /boot/grub/grub.cfg
insmod keylayouts
keymap $prefix/layouts/gb.gkb

9. If the machine uses UEFI rather than PC BIOS, update the GRUB files in the EFI directory.

root # grub-install --efi-directory=/boot/efi

10. Reboot to check if the gb keymap has been loaded for the GRUB shell.

root # reboot

When I press ‘c‘ when the GRUB menu appears, I now see the following if I press each key on the second-to-last row of keys on the keyboard:

grub> \zxcvbnm,./

That corresponds to a British English keyboard layout. As I mentioned before, due to GRUB’s limitations only standard ASCII chars are possible, so it is not possible to type characters such as é and è, or symbols such as £ and € etc. on the GRUB command line, whatever the keymap.

You can tell if the GRUB keylayouts module is loaded by entering the following command on the GRUB command line:

lsmod

Below is what I then see on the screen of a PC BIOS machine running up-to-date Gentoo Linux (Stable Branch) when I press ‘c‘ when the GRUB menu is displayed.

                                                GNU GRUB  version 2.02~beta3

   Minimal BASH-like line editing is supported. For the first word, TAB lists possible command completions. Anywhere else TAB lists possible device or file completions. ESC at any time exits.


grub> lsmod
Name    Ref Count       Dependencies
minicmd 1
gfxterm_background      1              bitmap,video,extcmd,gfxterm,bitmap_scale,video_colors
bitmap_scale    2               bitmap
video_colors    2
png     1               bitmap,bufio
bitmap  7
search  1               search_label,extcmd,search_fs_file,search_fs_uuid
search_label    2
search_fs_file  2
search_fs_uuid  2
at_keyboard     1               boot,keylayouts
keylayouts      3
gfxterm 3               video,font
all_video       1               video_cirrus,video_bochs,vga,vbe
video_cirrus    2               video_fb,pci,video
video_bochs     2               video_fb,pci,video
pci     6
vga     2               video_fb,video
vbe     2               video_fb,video
video_fb        12
font    5               video,bufio
video   24
loadenv 1               extcmd,disk
disk    2
test    1
normal  1               gettext,boot,extcmd,bufio,crypto,terminal
gzio    0
gettext 3
boot    4
extcmd  8
bufio   10
crypto  2
terminal        2
biosdisk        1
part_msdos      2
ext2    4               fshelp
fshelp  5
grub>

Shown below is what I see when I perform the following steps on the GRUB command line:

1. press each key on the second-to-last line of keys on the keyboard and press Enter;
2. check which GRUB terminal input module is loaded;
3. change from the British English keyboard layout to the Brazilian Portuguese keyboard layout;
4. press each key on the second-to-last line of keys on the keyboard and press Enter;
5. switch back to the British English keyboard layout;
6. press each key on the second-to-last line of keys on the keyboard and press Enter;
7. switch to the US English keyboard layout;
8. press each key on the second-to-last line of keys on the keyboard and press Enter;
9. switch back to the British English keyboard layout.

In each case the output on the screen is correct for the keyboard layout selected:

grub> \zxcvbnm,./
error: can't find command `zxcvbnm,./'.
grub> terminal_input
Active input terminals:
at_keyboard
Available input terminals:
console serial_* serial
grub> keymap br
grub> \zxcvbnm,.;
error: can't find command `zxcvbnm,.;'.
grub> keymap gb
grub> \zxcvbnm,./
error: can't find command `zxcvbnm,./'.
grub> keymap us
grub> <zxcvbnm,./
error: syntax error.
error: Incorrect command.
error: syntax error.
grub> keymap gb
grub> 

There is one more caveat…

When the GRUB menu first appears at boot, the following lines are still displayed at the bottom of the GRUB menu:

   Use the ↑ and ↓ keys to select which entry is highlighted.
   Press enter to boot the selected OS, `e' to edit the commands before booting or `c' for a command-line.
The highlighted entry will be executed automatically in 4s.

However, the highlighted entry on the GRUB menu is no longer executed automatically and I have to press ENTER in order to get GRUB to boot Linux. That is not a big deal in my case.

Automatically clearing the /usr/tmp/portage directory in Gentoo Linux

Gentoo Linux has been in use for nine years on one of my old laptops. A couple of days ago I performed the usual rolling update of the installation, but the latest version of a large package that normally takes several hours to compile failed to compile due to a lack of disk space. Sure enough, the command ‘df -h‘ showed me that the root partition was full. After a little digging I discovered that the directory /usr/tmp/portage/ contained a whopping 30GB of directories and files.

Portage uses the directory /usr/tmp/portage/ as a temporary store for the package source code when merging a package. The temporary files are not deleted if a merge fails, but the emerge command should delete them on the next merge of that package. On the other hand the ebuild command does not delete the temporary files, although normally you only use the ebuild command if you are creating a manifest.

Anyway, in the nine years that Gentoo Linux has been installed on the laptop I had never bothered to check that /usr/tmp/portage/ was actually empty, and its contents had slowly increased. The cure to my immediate problem was simply to empty the directory:

root # rm -rf /usr/tmp/portage/*

I doubt the laptop would still be working by the time /usr/tmp/portage would become that full again, but the situation got me thinking: What if I were to create a script to delete the temporary directories and files in /usr/tmp/portage/ at shutdown?

Gentoo Linux on this laptop uses OpenRC so I simply created a file /etc/local.d/99delete_tmp_files_from_failed_merges.stop containing the following code:

#!/bin/bash
# If root partition is more than 90% full, delete any temporary directories and
# files that were left in /var/tmp/portage/ instead of being deleted.
#
# The root partition is on /dev/sda6 and the emerge command must not be running.
#
if [ `pgrep -c emerge` -eq 0 ] && [ `df | awk '/sda6/ {print $5}' | awk -F% '{print $1}'` -gt 90 ]; then
    rm -rf /usr/tmp/portage/*
fi

I made the script executable:

root # chmod +x /etc/local.d/99delete_tmp_files_from_failed_merges.stop

Now, if the root partition is more than 90% full when I shut down the laptop, the script will automatically empty that directory. One less thing to think about.

HEIC image files in Linux

I was at an event recently where the attendees were asked to upload their camera and smartphone photos and videos to a shared Google Drive folder. Some of the uploaded photo files have a .HEIC (High Efficiency Image Container) extension, which I had not come across before. I have since learnt that these HEIC files were produced by iPhones running iOS 11, encoded using the HEIF (High Efficiency Image File) format. Apparently the HEIF format is superior to the JPEG format in a number of ways (see the links at the end of my post, especially the image examples given by Nokia), although it is subject to patents and therefore I believe there are certain constraints to coding image files in HEIC format. Anyway, I’ll leave you to read the fine print. My interest was simply because I wanted to be able to download the above-mentioned photo files and view them all in the file managers and image-viewing applications in Linux and Android on my various devices.

Now, I can browse and view the above-mentioned shared HEIC images in Google Drive in the Firefox and Chrome browsers in Linux, although an ownCloud site viewed using the same browsers displays the HEIC files as grey icons that can only be downloaded, not opened and viewed in the browser. I also found that Cirrus, the Android app for ownCloud that I use on my Galaxy Note 8 phone, cannot display HEIC photos either.

I downloaded the HEIC files to a machine running Lubuntu 18.04 and to a machine running Gentoo Linux. The file manager PCManFM in Lubuntu 18.04 displays grey icons rather than thumbnails for these HEIC files, and KDE’s Dolphin 18.08.3 file manager in Gentoo Linux displays green image icons rather than thumbnails for them. As far as Linux image viewers go, in Lubuntu 18.04 I find that GPicView 0.2.5 and Geeqie 1.4 cannot display HEIC images, and in Gentoo Linux KDE I find that GQview 2.1.5-r1, Okular 18.08.3 and Gwenview 18.08.3 cannot display HEIC images. So I set about converting all the HEIC files to JPG files. I managed to do this but needed to use a range of tools, as illustrated by a couple of examples below for Lubuntu 18.04 and Gentoo Linux. This post might seem long-winded but perhaps may be of help to Linux users coming across .HEIC files for the first time.

From the .HEIC files I had downloaded I picked one at random to try and convert to a JPG file: IMG_3706.HEIC. Its EXIF data confirms it is an HEIC file:

user $ exiftool IMG_3706.HEIC | grep "File Type"
File Type                       : HEIC
File Type Extension             : heic
user $ exiftool IMG_3706.HEIC | grep "Camera Model"
Camera Model Name               : iPhone 7 Plus

Several of the files with the .HEIC suffix that I downloaded were not real HEIC files according to their EXIF data:

user $ exiftool IMG_9474.HEIC | grep "File Type"
File Type                       : JPEG
File Type Extension             : jpg
user $ exiftool IMG_9474.HEIC | grep "Camera Model"
Camera Model Name               : iPhone 8

Those files were apparently treated as JPEG files by the tools I mention below, so I have omitted the results for those ‘false’ HEIC files.

Lubuntu 18.04

1. I installed the libheif example tools:

user $ sudo apt install libheif-examples

2. I used the heif-info command to check the file:

user $ heif-info IMG_3706.HEIC 
image: 3024x4032 (id=49), primary
  thumbnail: 240x320
  alpha channel: no
  depth channel: no

3. I tried to convert the file using the heif-convert command:

user $ heif-convert IMG_3706.HEIC IMG_3706.jpg
File contains 1 images
Written to IMG_3706.jpg

4. Apparently Imagemagick >=7.0.7-22 compiled with --with-libheif is supposed to be able to convert HEIC files to JPG. Anyway, I tried to convert the file using the current version of Imagemagick in Lubuntu 18.04 (the current package version is 8:6.9.7.4+dfsg-16ubuntu6.4):

user $ convert IMG_3706.HEIC IMG_3706a.jpg
convert-im6.q16: no decode delegate for this image format `HEIC' @ error/constitute.c/ReadImage/504.
convert-im6.q16: no images defined `IMG_3706a.jpg' @ error/convert.c/ConvertImageCommand/3258.

5. Apparently the GIMP >=2.10.2 supports HEIF by using heif-gimp-plugin. Anyway, I tried to open the file with the current version of the GIMP in Lubuntu 18.04 (the current package version is 2.8.22-1). The GIMP launches and pops-up a window with the title ‘GIMP Message’ containing the following message and an ‘OK’ button:

GIMP Message
Opening /home/fitzcarraldo/IMG_3706.HEIC’ failed: Unknown file type

6. I used the online tool ‘libheif decoder demo’ (https://strukturag.github.io/libheif/) in a browser window. This can load the file IMG_3706.HEIC (‘Browse…’ button) and convert it (‘Save image…’ button) to IMG_3706.jpeg.

Gentoo Linux with KDE 5

1. I installed the libheif example tools implicitly by re-merging Imagemagick with USE="heif", which installs libheif.

root # cat /etc/portage/package.use/imagemagick 
media-gfx/imagemagick heif
root # emerge imagemagick

2. I used the heif-info command to check the file:

user $ heif-info IMG_3706.HEIC  
image: 3024x4032 (id=49), primary
  thumbnail: 240x320
  alpha channel: no
  depth channel: no

3. I tried to convert the file using the heif-convert command:

user $ heif-convert IMG_3706.HEIC IMG_3706.jpg
File contains 1 images
Written to IMG_3706.jpg

4. I tried to convert the file using Imagemagick >=7.0.7-22 compiled with --with-libheif (Imagemagick merged with USE="heif"):

user $ convert IMG_3706.HEIC IMG_3706a.jpg
user $

So Imagemagick 7.0.8.16 in Gentoo has no trouble with the file IMG_3706.HEIC.

5. I tried to open the file with the GIMP >=2.10.2, which supports HEIF using heif-gimp-plugin (GIMP >=2.10.6-r1 with USE="heif" in the case of Gentoo Linux)

First I re-merged the GIMP with the heif USE flag:

root # cat /etc/portage/package.accept_keywords/gimp
=media-gfx/gimp-2.10.8-r1 ~amd64
# required by media-gfx/gimp-2.10.8-r1::gentoo
=media-libs/libmypaint-1.3.0 ~amd64
# required by media-gfx/gimp-2.10.8-r1::gentoo
=media-gfx/mypaint-brushes-1.3.0-r1 ~amd64
# required by media-gfx/gimp-2.10.8-r1::gentoo
=media-libs/gegl-0.4.12 ~amd64
# required by media-gfx/gimp-2.10.8-r1::gentoo
=media-libs/babl-0.1.60 ~amd64
root # cat /etc/portage/package.use/gimp
media-gfx/gimp heif
root # emerge -1vp gimp

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild  N    ~] media-gfx/mypaint-brushes-1.3.0-r1:1.0::gentoo  2,390 KiB
[ebuild     U ~] media-libs/babl-0.1.60::gentoo [0.1.38::gentoo] USE="(-altivec)" CPU_FLAGS_X86="mmx sse sse2 sse3%* sse4_1 -f16c" 670 KiB
[ebuild  N     ] media-libs/gexiv2-0.10.8::gentoo  USE="-introspection -python -static-libs -test -vala" PYTHON_TARGETS="python2_7 python3_6 -python3_4 -python3_5" 620 KiB
[ebuild  NS   ~] media-libs/gegl-0.4.12:0.4::gentoo [0.2.0-r5:0::gentoo] USE="cairo ffmpeg introspection lcms openexr sdl svg tiff v4l -debug -jpeg2k -lensfun -libav -raw -test -umfpack -vala -webp" CPU_FLAGS_X86="mmx sse" 6,900 KiB
[ebuild  NS    ] media-libs/gegl-0.3.26:0.3::gentoo [0.2.0-r5:0::gentoo] USE="cairo ffmpeg introspection lcms openexr sdl svg tiff v4l -debug -jpeg2k -lensfun -raw -test -umfpack -vala -webp" CPU_FLAGS_X86="mmx sse" 6,378 KiB
[ebuild  N    ~] media-libs/libmypaint-1.3.0::gentoo  USE="gegl nls openmp -introspection" 428 KiB
[ebuild     U ~] media-gfx/gimp-2.10.8-r1:2::gentoo [2.8.22-r1:2::gentoo] USE="alsa heif%* mng openexr%* udev wmf -aalib (-altivec) (-aqua) -debug -doc -gnome -jpeg2k -postscript -python -smp -test -unwind% -vector-icons% -webp% -xpm (-bzip2%*) (-curl%) (-dbus%*) (-exif%*) (-jpeg%*) (-lcms%*) (-pdf%*) (-png%*) (-svg%*) (-tiff%*)" CPU_FLAGS_X86="mmx sse" PYTHON_TARGETS="python2_7" 31,206 KiB

Total: 7 packages (2 upgrades, 3 new, 2 in new slots), Size of downloads: 48,591 KiB

I then launched the GIMP and successfully opened the file IMG_3706.HEIC, and I was able to export it as IMG_3706.jpg.

6. As would be expected, the online tool ‘libheif decoder demo’ (https://strukturag.github.io/libheif/) behaves exactly the same in Gentoo Linux as it does in Lubuntu 18.04 (see earlier).

Summary

So there you have it; if the Linux file manager and/or image viewing applications you use cannot already handle HEIC files, the tools in Linux that I found may work are as follows:

• heif-convert (from the package libheif-examples in Ubuntu/Lubuntu, or from from the package libheif in Gentoo).
• Imagemagick (not every version).
• The GIMP (not every version).
• the online tool ‘libheif decoder demo’ (https://strukturag.github.io/libheif/).

I have not tried the copyright open-source code from Nokia (see link under Further Reading below), qt-heif-image-plugin and tifig (not in active development). If you have had success using another tool to convert HEIC files, please post a comment below for the benefit of other users, giving the name of the tool, the package name and version, and the Linux distribution (including release number, if not a rolling distribution).

Further reading

1. Wikipedia – High Efficiency Image File Format
2. Lifewire – What Are HEIF and HEIC, and Why Is Apple Using Them?
3. Nokia – High Efficiency Image File Format (HEIF)
4. libheif – a ISO/IEC 23008-12:2017 HEIF file format decoder and encoder
5. askubuntu – Any app on Ubuntu to open HEIF (.heic, High Efficiency Image File Format) pictures?

A brief discussion about package installation times in Gentoo Linux

I thought that perhaps users of binary-based Linux distributions who are contemplating trying out the source-based distribution Gentoo Linux might be interested to know a bit about package installation times in contrast to binary distributions. I am not going to go into great detail here; this is just to give interested people a quick idea of possible package installation times in Gentoo Linux.

The package manager of a binary-based distribution such as Ubuntu downloads and installs ‘binary’ packages, i.e. packages containing pre-built executables. On the other hand, Gentoo’s package manager Portage downloads source-code packages and builds the binaries (executables) on your machine. Nevertheless, a small number of Portage packages contain binaries rather than source code, either because the source code could take many hours to build on older hardware or because the source code is simply not available in the public domain. An example of the first scenario is Firefox, which is available in Gentoo both as the source code package www-client/firefox and as the binary package www-client/firefox-bin so that the user can choose which to install (‘merge’, in Gentoo parlance). An example of the second scenario is TeamViewer, which is only available as the binary package net-misc/teamviewer because TeamViewer is closed-source software (i.e. the company that develops TeamViewer does not release its source code).

Clearly, installing an application from a package containing source code that has to be compiled and linked on your machine will take longer than installing the application from a package containing the executable binary that someone else has already built. The time to install from source-code packages of course depends on the precise package (some can take only a minute or so to install), the power of the machine on which the package is being installed, and various other factors.

I currently have two laptops running Gentoo Linux: one is over eight years old with an early Intel Core i7-720QM (throttled to 933 MHz because of the small PSU); the other is three and a half years old and has a newer Intel Core i7-4810MQ (2.8 GHz). Although the older laptop is slow by today’s standards, the newer laptop is still reasonably powerful. Even so, those few large source-code packages such as Firefox, Chromium and LibreOffice can take quite a long time to install, as illustrated below for Firefox by using the Gentoo utility genlop to find out the time it took to install:

clevow230ss /home/fitzcarraldo # genlop -t firefox | tail -n 3
     Wed Sep 26 19:53:47 2018 >>> www-client/firefox-62.0.2
       merge time: 1 hour, 4 minutes and 22 seconds.

On the other hand, installing TeamViewer took no time at all:

clevow230ss /home/fitzcarraldo # # genlop -t teamviewer | tail -n 3
     Mon Oct  1 21:39:29 2018 >>> net-misc/teamviewer-13.2.13582
       merge time: 16 seconds.

And youtube-dl also installed quickly:

clevow230ss /home/fitzcarraldo # genlop -t youtube-dl | tail -n 3
     Mon Oct  1 21:42:26 2018 >>> net-misc/youtube-dl-2018.09.26
       merge time: 53 seconds.

I also used to run Gentoo Linux on a 1998 Gateway Solo 9300 laptop (Intel Mobile Pentium III Coppermine 800 MHz). Neither its CPU nor its 288 MB RAM could cope with building large source code packages such as Firefox and LibreOffice, so on that machine I installed www-client/firefox-bin and app-office/libreoffice-bin instead.

Anyway, now let’s have a quick look at a typical package upgrade session, which I aim to perform at least once a week. On the above-mentioned newer laptop today I upgraded all installed packages that had newer versions available in the so-called Portage ‘tree’. This amounted to installing (‘merging’) the following fifteen packages:

1. net-analyzer/traceroute-2.1.0
2. media-libs/exiftool-11.03
3. dev-libs/libtasn1-4.13
4. x11-misc/shared-mime-info-1.10
5. x11-libs/libxcb-1.13.1
6. media-libs/x265-2.8
7. dev-libs/redland-1.0.17-r1
8. media-libs/mesa-18.1.9
9. dev-libs/dbus-glib-0.110
10. sys-power/upower-0.99.8
11. app-text/libspectre-0.2.8
12. app-crypt/pinentry-1.1.0-r2
13. net-im/pidgin-2.13.0
14. app-emulation/wine-vanilla-3.17
15. media-video/handbrake-1.1.1

It took just under thirty-four minutes to install the above fifteen packages on my newer laptop. Below is what the upgrade process looked like in a terminal window. I have used the package manager’s long command options here, but normally I would use the single-letter shortcuts. As the focus of this post is on package installation time, I will not bother to show the command I used before this to synchronise (update) package information on the laptop with the remote package servers.

clevow230ss /home/fitzcarraldo # emerge --update --verbose --deep --newuse --with-bdeps=y --keep-going @world

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild     U  ] net-analyzer/traceroute-2.1.0::gentoo [2.0.20::gentoo] USE="-static" 70 KiB
[ebuild     U  ] media-libs/exiftool-11.03::gentoo [10.95::gentoo] USE="-doc" 4,311 KiB
[ebuild   R    ] dev-libs/libtasn1-4.13:0/6::gentoo  USE="-doc -static-libs -test% -valgrind" ABI_X86="32 (64) (-x32)" 0 KiB
[ebuild     U  ] x11-misc/shared-mime-info-1.10::gentoo [1.9::gentoo] USE="-test" 603 KiB
[ebuild     U  ] x11-libs/libxcb-1.13.1:0/1.12::gentoo [1.13:0/1.12::gentoo] USE="xkb -doc (-selinux) -static-libs -test" ABI_X86="32 (64) (-x32)" 495 KiB
[ebuild  r  U  ] media-libs/x265-2.8:0/160::gentoo [2.6:0/146::gentoo] USE="10bit 12bit -numa -pic (-power8) -test" ABI_X86="(64) -32 (-x32)" 1,348 KiB
[ebuild     U  ] dev-libs/redland-1.0.17-r1::gentoo [1.0.16::gentoo] USE="berkdb -iodbc -mysql -odbc -postgres -sqlite -static-libs (-xml%*)" 1,584 KiB
[ebuild     U  ] media-libs/mesa-18.1.9::gentoo [18.1.6::gentoo] USE="classic dri3 egl gallium gbm llvm nptl wayland -bindist -d3d9 -debug -gles1 -gles2 -opencl -openmax -osmesa -pax_kernel -pic (-selinux) -unwind -vaapi -valgrind -vdpau -vulkan -xa -xvmc" ABI_X86="32 (64) (-x32)" VIDEO_CARDS="i915 i965 intel (-freedreno) (-imx) -nouveau -r100 -r200 -r300 -r600 -radeon -radeonsi (-vc4) -virgl (-vivante) -vmware" 10,885 KiB
[ebuild     U  ] dev-libs/dbus-glib-0.110::gentoo [0.108::gentoo] USE="-debug -static-libs -test" ABI_X86="(64) -32 (-x32)" 817 KiB
[ebuild     U  ] sys-power/upower-0.99.8:0/3::gentoo [0.99.5:0/3::gentoo] USE="introspection -doc -ios (-selinux)" 439 KiB
[ebuild     U  ] app-text/libspectre-0.2.8::gentoo [0.2.7::gentoo] USE="-debug -doc -static-libs" 412 KiB
[ebuild     U  ] app-crypt/pinentry-1.1.0-r2::gentoo [1.0.0-r2::gentoo] USE="gnome-keyring gtk ncurses qt5 -caps -emacs -fltk% -static" 457 KiB
[ebuild     U  ] net-im/pidgin-2.13.0:0/2::gentoo [2.12.0:0/2::gentoo] USE="dbus gnutls gstreamer gtk ncurses networkmanager nls spell xscreensaver zeroconf (-aqua) -debug -doc -eds -gadu -groupwise -idn -meanwhile -perl -pie -prediction -python -sasl -silc -tcl -tk -zephyr" PYTHON_TARGETS="python2_7" 8,784 KiB
[ebuild  NS   ~] app-emulation/wine-vanilla-3.17:3.17::gentoo [3.16:3.16::gentoo] USE="X alsa cups fontconfig gecko gphoto2 gsm jpeg lcms mp3 ncurses nls openal opengl perl png pulseaudio realtime run-exes scanner sdl ssl threads truetype udev udisks v4l xcomposite xml -capi -custom-cflags -dos -gssapi -gstreamer -kerberos -ldap -mono -netapi -odbc -opencl -osmesa -oss -pcap -prelink -samba (-selinux) -test -vkd3d -vulkan -xinerama" ABI_X86="32 64 (-x32)" 20,955 KiB
[ebuild  rR   ~] media-video/handbrake-1.1.1::gentoo  USE="fdk gstreamer gtk x265 -libav -libav-aac" 0 KiB

Total: 15 packages (12 upgrades, 1 in new slot, 2 reinstalls), Size of downloads: 51,156 KiB

The following packages are causing rebuilds:

  (media-libs/x265-2.8:0/160::gentoo, ebuild scheduled for merge) causes rebuilds for:
    (media-video/handbrake-1.1.1:0/0::gentoo, ebuild scheduled for merge)

>>> Verifying ebuild manifests
>>> Running pre-merge checks for app-emulation/wine-vanilla-3.17
>>> Emerging (1 of 15) net-analyzer/traceroute-2.1.0::gentoo
>>> Emerging (2 of 15) media-libs/exiftool-11.03::gentoo
>>> Emerging (3 of 15) dev-libs/libtasn1-4.13::gentoo
>>> Installing (1 of 15) net-analyzer/traceroute-2.1.0::gentoo
>>> Installing (2 of 15) media-libs/exiftool-11.03::gentoo
>>> Installing (3 of 15) dev-libs/libtasn1-4.13::gentoo
>>> Emerging (4 of 15) x11-misc/shared-mime-info-1.10::gentoo
>>> Installing (4 of 15) x11-misc/shared-mime-info-1.10::gentoo
>>> Emerging (5 of 15) x11-libs/libxcb-1.13.1::gentoo
>>> Installing (5 of 15) x11-libs/libxcb-1.13.1::gentoo
>>> Emerging (6 of 15) media-libs/x265-2.8::gentoo
>>> Emerging (7 of 15) dev-libs/redland-1.0.17-r1::gentoo
>>> Emerging (8 of 15) media-libs/mesa-18.1.9::gentoo
>>> Installing (7 of 15) dev-libs/redland-1.0.17-r1::gentoo
>>> Installing (6 of 15) media-libs/x265-2.8::gentoo
>>> Installing (8 of 15) media-libs/mesa-18.1.9::gentoo
>>> Emerging (9 of 15) dev-libs/dbus-glib-0.110::gentoo
>>> Installing (9 of 15) dev-libs/dbus-glib-0.110::gentoo
>>> Emerging (10 of 15) sys-power/upower-0.99.8::gentoo
>>> Emerging (11 of 15) app-text/libspectre-0.2.8::gentoo
>>> Emerging (12 of 15) app-crypt/pinentry-1.1.0-r2::gentoo
>>> Installing (10 of 15) sys-power/upower-0.99.8::gentoo
>>> Installing (11 of 15) app-text/libspectre-0.2.8::gentoo
>>> Installing (12 of 15) app-crypt/pinentry-1.1.0-r2::gentoo
>>> Emerging (13 of 15) net-im/pidgin-2.13.0::gentoo
>>> Emerging (14 of 15) app-emulation/wine-vanilla-3.17::gentoo
>>> Emerging (15 of 15) media-video/handbrake-1.1.1::gentoo
>>> Installing (15 of 15) media-video/handbrake-1.1.1::gentoo
>>> Installing (13 of 15) net-im/pidgin-2.13.0::gentoo
>>> Installing (14 of 15) app-emulation/wine-vanilla-3.17::gentoo
>>> Jobs: 15 of 15 complete                         Load avg: 2.94, 5.84, 6.01
>>> Auto-cleaning packages...

>>> No outdated packages were found on your system.

 * Regenerating GNU info directory index...
 * Processed 129 info files.
 * After world updates, it is important to remove obsolete packages with
 * emerge --depclean. Refer to `man emerge` for more information.
 

The genlop tool in Gentoo can be used to check chronologically which packages were installed and removed. For example:

clevow230ss /home/fitzcarraldo # genlop -l | grep "Mon Oct  1"
     Mon Oct  1 18:16:19 2018 >>> net-analyzer/traceroute-2.1.0
     Mon Oct  1 18:16:27 2018 >>> media-libs/exiftool-11.03
     Mon Oct  1 18:16:49 2018 >>> dev-libs/libtasn1-4.13
     Mon Oct  1 18:17:02 2018 >>> x11-misc/shared-mime-info-1.10
     Mon Oct  1 18:17:49 2018 >>> x11-libs/libxcb-1.13.1
     Mon Oct  1 18:19:11 2018 >>> dev-libs/redland-1.0.17-r1
     Mon Oct  1 18:28:07 2018 >>> media-libs/x265-2.8
     Mon Oct  1 18:28:14 2018 >>> media-libs/mesa-18.1.9
     Mon Oct  1 18:28:30 2018 >>> dev-libs/dbus-glib-0.110
     Mon Oct  1 18:28:52 2018 >>> sys-power/upower-0.99.8
     Mon Oct  1 18:28:57 2018 >>> app-text/libspectre-0.2.8
     Mon Oct  1 18:29:03 2018 >>> app-crypt/pinentry-1.1.0-r2
     Mon Oct  1 18:30:02 2018 >>> media-video/handbrake-1.1.1
     Mon Oct  1 18:30:34 2018 >>> net-im/pidgin-2.13.0
     Mon Oct  1 18:47:45 2018 >>> app-emulation/wine-vanilla-3.17
clevow230ss /home/fitzcarraldo #

When packages are being upgraded, the package manager will inform you if a package has an update to the associated application’s configuration file. Even if the package manager does not indicate that any configuration files need to be updated, it does no harm to check anyway:

clevow230ss /home/fitzcarraldo # etc-update
Scanning Configuration files...
Exiting: Nothing left to do; exiting. :)

To remove packages that are no longer required (either because the package is no longer a dependency or because a newer version of a slotted* package has been installed), the ‘depclean‘ option is used. Below is what happened when I used that option to clean up after the above-mentioned fifteen packages were upgraded/re-installed.

* Some Gentoo packages are ‘slotted’, i.e. more than one version of the package can be installed and used concurrently. Examples include WINE, Python and kernel sources.

clevow230ss /home/fitzcarraldo # emerge --ask --depclean

 * Always study the list of packages to be cleaned for any obvious
 * mistakes. Packages that are part of the world set will always
 * be kept.  They can be manually added to this set with
 * `emerge --noreplace `.  Packages that are listed in
 * package.provided (see portage(5)) will be removed by
 * depclean, even if they are part of the world set.
 * 
 * As a safety measure, depclean will not remove any packages
 * unless *all* required dependencies have been resolved.  As a
 * consequence of this, it often becomes necessary to run 
 * `emerge --update --newuse --deep @world` prior to depclean.

Calculating dependencies... done!
>>> Calculating removal order...

>>> These are the packages that would be unmerged:                                                                                                                                           

 app-emulation/wine-vanilla
    selected: 3.16 
   protected: none 
     omitted: 3.17 

 dev-python/pyliblzma
    selected: 0.5.3-r1 
   protected: none 
     omitted: none 

 dev-python/twisted-web
    selected: 15.2.1 
   protected: none 
     omitted: none 

 dev-python/psutil
    selected: 5.4.3 
   protected: none 
     omitted: none 

 dev-python/twisted-core
    selected: 15.2.1 
   protected: none 
     omitted: none 

 dev-python/service_identity
    selected: 16.0.0 
   protected: none 
     omitted: none 

 dev-python/pyasn1-modules
    selected: 0.0.8 
   protected: none 
     omitted: none 

 dev-python/attrs
    selected: 16.3.0-r1 
   protected: none 
     omitted: none 

 dev-python/zope-interface
    selected: 4.4.3 
   protected: none 
     omitted: none 

 dev-python/namespace-zope
    selected: 1 
   protected: none 
     omitted: none 

All selected packages: =dev-python/pyliblzma-0.5.3-r1 =dev-python/namespace-zope-1 =dev-python/zope-interface-4.4.3 =dev-python/pyasn1-modules-0.0.8 =app-emulation/wine-vanilla-3.16 =dev-python/psutil-5.4.3 =dev-python/twisted-web-15.2.1 =dev-python/twisted-core-15.2.1 =dev-python/service_identity-16.0.0 =dev-python/attrs-16.3.0-r1

>>> 'Selected' packages are slated for removal.
>>> 'Protected' and 'omitted' packages will not be removed.

Would you like to unmerge these packages? [Yes/No] Yes
>>> Waiting 5 seconds before starting...
>>> (Control-C to abort)...
>>> Unmerging in: 5 4 3 2 1
>>> Unmerging (1 of 10) app-emulation/wine-vanilla-3.16...
>>> Unmerging (2 of 10) dev-python/pyliblzma-0.5.3-r1...
>>> Unmerging (3 of 10) dev-python/twisted-web-15.2.1...
>>> Unmerging (4 of 10) dev-python/psutil-5.4.3...
>>> Unmerging (5 of 10) dev-python/twisted-core-15.2.1...
>>> Unmerging (6 of 10) dev-python/service_identity-16.0.0...
>>> Unmerging (7 of 10) dev-python/pyasn1-modules-0.0.8...
>>> Unmerging (8 of 10) dev-python/attrs-16.3.0-r1...
>>> Unmerging (9 of 10) dev-python/zope-interface-4.4.3...
>>> Unmerging (10 of 10) dev-python/namespace-zope-1...
Packages installed:   1714
Packages in world:    198
Packages in system:   43
Required packages:    1714
Number removed:       10

 * GNU info directory index is up-to-date.

As you can see above, the package manager found a number of installed packages that were no longer required, either because a new version of a slotted package had been installed (notice wine-vanilla) or because they are no longer dependencies. As I did not want to keep both wine-3.16 and wine-3.17 installed simultaneously, I simply replied ‘Yes’. By the way, the depclean option can also be used to remove (uninstall) older versions of an individual slotted package:

clevow230ss /home/fitzcarraldo # emerge --ask --depclean wine-vanilla

It can also be used to remove an individual package if it is not a dependency. For example, the following command does not allow me to remove the installed package vlc because other installed packages depend on it:

clevow230ss /home/fitzcarraldo # emerge --ask --depclean vlc

Calculating dependencies... done!
>>> No packages selected for removal by depclean
>>> To see reverse dependencies, use --verbose
Packages installed:   1714
Packages in world:    198
Packages in system:   43
Required packages:    1714
Number removed:       0

Whereas the following command would allow me to remove the installed package winetricks because no other installed package depends on it:

clevow230ss /home/fitzcarraldo # emerge --ask --depclean winetricks

Calculating dependencies... done!
>>> Calculating removal order...

>>> These are the packages that would be unmerged:                                                                                                                                           

 app-emulation/winetricks
    selected: 20180815 
   protected: none 
     omitted: none 

All selected packages: =app-emulation/winetricks-20180815

>>> 'Selected' packages are slated for removal.
>>> 'Protected' and 'omitted' packages will not be removed.

Would you like to unmerge these packages? [Yes/No] No

Quitting.

Packages installed:   1714
Packages in world:    198
Packages in system:   43
Required packages:    1713
Number to remove:     1

Anyway, I hope this post has given potential adopters a rough idea of installation times in Gentoo Linux, even if it is far from thorough.